Method of depositing an inorganic film on an organic polymer

ABSTRACT

Inorganic materials are deposited onto organic polymers using ALD methods. Ultrathin, conformal coatings of the inorganic materials can be made in this manner. The coated organic polymers can be used as barrier materials, as nanocomposites, as catalyst supports, in semiconductor applications, in coating applications as well as in other applications.

[0001] Organic polymers are used in countless applications because oftheir many desirable properties. Various polymers have desirableattributes for specific applications. Those attributes can include lowcost, strength, insulating nature, biocompatibility and flexibility.However, there are many properties that could be improved by theaddition of an inorganic film to the polymer surface.

[0002] For various reasons, inorganic coatings on polymers are expectedto provide desirable properties. For example, the gas permeabilitythrough most polymers is quite high for gases such as hydrocarbons, H₂Oand O₂. This gas permeability affects the quality of polymers used forfood and medical packaging. H₂O and O₂ can diffuse into the package fromthe outside and degrade its contents. Inorganic films, such as Al₂O₃ andSiO₂ films are much less permeable than polymers. Such films couldpotentially form a diffusion barrier to prevent gas permeability inpolymer films.

[0003] In the synthesis of polymeric panels for vehicles, constructionor other applications requiring resistance to sunlight and theenvironment, inorganic films, such as Al₂O₃ and SiO₂ oxide films, canprovide protection from ultraviolet light, heat, abrasion, andchemicals. Such films can be applied to the exterior of fabricatedpolymeric components to protect them from the environment.

[0004] For other applications, it would be desirable to deposit anadherent coating of a catalytic material onto an organic polymer, toform a supported catalyst. Such polymer-based catalysts would be usefulfor gas phase polymerization processing. Currently, silica or alumina isused as the catalyst supports. This leads to contamination of the newpolymer with residual silica or alumina. This contamination could beminimized if the monolithic silica or alumina based catalyst supportscould be replaced with a polymer support.

[0005] In the area of microelectronics, polymers are used as lowdielectric constant (low k) insulating films. Deposition on these low kfilms is difficult. The deposition of an oxide layer on the polymersubstrate surface may provide a base surface layer that allowsdeposition of other materials. One such material is titanium nitride,which is used as a copper diffusion barrier. The oxide layer may alsofacilitate the etching of metals more easily than could be achieveddirectly on the polymer surface.

[0006] Deposition of inorganic films on organic polymer surfaces isdifficult. Chemical vapor deposition (CVD) methods usually cannot beused because the CVD temperatures are above the softening or pyrolysistemperatures for the polymers. Physical sputtering or plasma depositioncan be employed at low temperatures to form oxide films such as Al₂O₃ orSiO₂. However, sputtering requires line-of-sight to the polymer surfaceand is not effective for shadowed structures or particles. Plasmadeposition involves high-energy particles that can damage and corrodethe polymer surface. Both sputtering and plasma deposition also leavedefects and pinholes in the deposited inorganic film that provide pathsfor H₂O and O₂ gas diffusion through the inorganic film. Both of thesecharacteristics are important for applications in food and medicalpackaging that require a transparent diffusion barrier on the polymersurface.

[0007] In addition, sputtering requires a special apparatus and highmaintenance sputtering targets. More significantly, sputtering can coatonly a limited area and requires line-of-sight to the polymer surface.Therefore, sputtering is not effective for coating shadowed structuresor particles. Plasma deposition also requires a plasma generation sourceand involves high-energy species. Although these species can react withthe polymer and functionalize the surface, they can also corrode thepolymer. Consequently, the plasma deposition of oxide films can damagethe underlying organic polymer substrate.

[0008] It would be desirable to provide a method to deposit very thincoatings of inorganic materials onto polymer substrates. It wouldfurther be desirable to provide organic polymers having thin deposits ofinorganic materials adhered to the polymer.

[0009] The invention is in one aspect a method for depositing aninorganic material on a polymer substrate material comprising,conducting a sequence of at least two self-limiting reactions at thesurface of said polymer substrate to deposit the inorganic material ontothe surface of said polymer substrate.

[0010] In another aspect, the invention is a polymer substrate havingdeposited thereon an inorganic material in the form of a film ordiscrete particles having a thickness of 200 nm or less. In preferredaspects, the inorganic material acts as an adhesion layer upon which asecond inorganic material is deposited. The adhesion layer permits thedeposition of materials that otherwise adhere poorly to the polymersubstrate.

[0011] In a third aspect, the invention is a nanocomposite prepared fromthe polymer substrate of the second aspect.

[0012] In a fourth aspect, the invention is a fabricated article madefrom the polymer substrate of the second aspect.

[0013] In a fifth aspect, the invention is a semiconductor devicecomprising a copper or aluminum interconnect insulated with the polymersubstrate of the second aspect.

[0014] In this invention, an inorganic material is deposited onto thesurface of an organic polymer using an atomic layer deposition (“ALD”;also known as ALE—“atomic layer epitaxy”). ALD techniques permit theformation of inorganic deposits approximately equal to the molecularspacing of the inorganic material, typically up to about 0.3 nm ofthickness per reaction cycle. In the ALD process, the inorganic depositis formed in a series of two or more self-limited reactions, which inmost instances can be repeated to sequentially form additional materialuntil the inorganic deposit achieves a desired size or thickness (suchas in the case of a film).

[0015] A wide variety of polymers may be used as substrates. Thesubstrate polymer may be thermoplastic or thermosetting, crosslinked ornon-crosslinked, and if not crosslinked, linear or branched. Further,the substrate polymer may exist in any physical form at the time theinorganic material is deposited, provided that the temperature is suchthat the substrate polymer is a solid. For example, the substratepolymer may be a particulate material having any desirable particlesize, such as, for example, about from 0.001 micron, preferably fromabout 0.05 micron and more preferably from about 1 micron, to 1millimeter or more, especially to about 200 microns and more preferablyto about 50 to 200 microns. Preferred particulate polymers have surfaceareas in the range of about 0.1 to 200 m²/g or more.

[0016] Polymer films are substrates of particular interest, such asmonolayer or multilayer films (that may be prepared by coextrusionprocesses, for example) having a thickness of 0.0005 to about 0.010inches. Polymer sheets having thicknesses of 0.010 inches or more areuseful substrates as well. Molded articles of all types (made by anyapplicable molding process, such as extrusion, compression molding,vacuum forming, thermoforming, injection molding, and the like) may beused as substrates.

[0017] The chemical composition of the substrate polymer may varywidely. Substrate polymers that contain functional groups such ashalogen, hydroxyl, carbonyl, carboxylic acid, primary amine, secondaryamine and the like are useful, as these functional groups provide sitesat which it is possible to form chemical bonds between the polymer andthe inorganic material. Examples of polymers having such functionalgroups are polyurethanes; polyesters (aliphatic and/or aromatic,including polyethylene terephthalate), epoxy resins, epoxy-novalacresins, phenolic resins, cellulose ethers and esters (such ashydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose,methyl hydroxylpropyl cellulose, and the like), polyvinyl alcohol,polyvinyl chloride, polyamides (such as the various nylons), polyamines,polyvinylidene chloride, halogenated or aminated poly(alkenyl aromatic)polymers, polyacrylic acid, polyacrylates, especially polymers orcopolymers of an hydroxyalkyl ester of acrylic or methacrylic acid;polyacrylamide; polyimides, polycarbonates and the like. In the cases ofcertain thermosetting resins such as phenolic, epoxy and epoxy-novalacresins, a solid B-staged resin can be used as the substrate, as well asthe fully cured resin.

[0018] However, polymers that do not contain such functional groups arealso useful as substrates. Among polymers of this type are thepolyolefins, such as low density polyethylene, linear low densitypolyethylene, substantially linear polyethylene, high densitypolyethylene, polypropylene, polybutylene, and various copolymers ofmonoalkenes; poly(alkenyl aromatic) polymers such as polystyrene andpoly(naphthalene); polymers of conjugated dienes such as polybutadiene,isoprene, and the like; PTFE, as well as block and/or random copolymersof any of the foregoing. Organosilicone polymers are likewise useful.

[0019] It is possible in some instances to perform a precursor reactionto introduce desirable functional groups onto the surface of the polymersubstrate. Depending on the particular polymer, techniques such as waterplasma treatment, ozone treatment, ammonia treatment and hydrogentreatment are among the useful methods of introducing functional groups.

[0020] The polymer substrate should be treated before initiating thereaction sequence to remove volatile materials that may be absorbed ontothe surface. This is readily done by exposing the substrate to elevatedtemperatures and/or vacuum. The polymer substrate is then sequentiallycontacted with gaseous reactants. The reactions are performed at atemperature below that at which the organic polymer degrades, melts, orsoftens enough to lose its physical shape. Many polymers degrade, meltor soften at moderately elevated (e.g., 400-550K) temperatures. Thetemperature at which the ALD reactions are conducted is thereforegenerally below 550K, and preferably below 400K, more preferably belowabout 373K, and especially below 350K, with the upper temperature limitbeing dependent on the particular organic polymer to be coated. Thereactants are gasses at the temperature the reactions are conducted.Particularly preferred reactants have vapor pressures of at least 10torr or greater at a temperature of 300K. In addition, the reactants areselected such that they can engage in the reactions that form theinorganic material at the temperatures stated above. Catalysts may beused to promote the reactions at the required temperatures.

[0021] At close to the softening temperature, the chains in the polymerare in thermal agitation and mobile. Pyrolysis of the polymer begins todegrade the polymer by desorbing monomers from the polymer. This loss ofmonomers exposes free radical carbon chains close to the surface of thepolymer. The thermal motion of the polymer chains and desorption ofmonomer units from the polymer is believed to provide functional groupson the surface of the polymer of reaction with the ALD reactants.Further, adsorption of the ALD reactants is believed to be facilitatedby the polymer chain mobility. Thus, conducting the ALD reactionsequences at elevated temperatures close to but below the softeningtemperature of the polymer substrate is desirable in some instances.

[0022] The polymer substrate is generally held in a chamber that can beevacuated to low pressures. Each reactant is introduced sequentiallyinto the reaction zone, typically together with an inert carrier gas.Before the next reactant is introduced, the reaction by-products andunreacted reagents are removed. This can be done, for example, bysubjecting the substrate to a high vacuum, such as about 10⁻⁵ torr orlower, after each reaction step. Another method of accomplishing this,which is more readily applicable for industrial application, is to sweepthe substrate with an inert purge gas between the reaction steps. Thispurge gas can also act as a carrier for the reagents. The next reactantis then introduced, where it reacts at the surface of the substrate.After removing excess reagents and reaction by-products, as before, thereaction sequence can be repeated as needed to build inorganic depositsof the desired size or thickness.

[0023] General methods for conducting ALD processes are described, forexample, in J. W. Klaus et al, “Atomic Layer Controlled Growth of SiO₂Films Using Binary Reaction Sequence Chemistry”, Appl. Phys. Lett. 70,1092 (1997) and O. Sheh et al., “Atomic Layer Growth of SiO₂ on Si(100)and H₂O using a Binary Reaction Sequence”, Surface Science 334, 135(1995).

[0024] A convenient method for depositing the inorganic material onto aparticulate polymer substrate is to form a fluidized bed of theparticles, and then pass the various reagents in turn through thefluidized bed under reaction conditions. Methods of fluidizingparticulate materials are well known, and generally include supportingthe particles on a porous plate or screen. A fluidizing gas is passedupwardly through the plate or screen, lifting the particles somewhat andexpanding the volume of the bed. With appropriate expansion, theparticles behave much as a fluid. The reagents can be introduced intothe bed for reaction with the surface of the particles. In thisinvention, the fluidizing gas also can act as an inert purge gas forremoving unreacted reagents and volatile or gaseous reaction productsand as a carrier for the reagents. In the case of fluidizing extremelyfine particles, vibration can be applied to assist in the fluidizationprocess. Vibrational forces are beneficial to overcome interparticle vander Waals forces that tend to prevent fluidization and promote a plugflow of particles in the bed. Ultra-fine, in particular, submicron andsmall micron sized-particles tend to form particle agglomerates thatmaintain fluidization in the bed and are not carried out with theoutflowing gas. Applying vibrational forces allows each primary particlein the bed to be coated individually instead of merely coating theagglomerate.

[0025] Another method for depositing the inorganic material onto aparticulate polymer substrate is through the use of a rotary tubereactor. The rotary tube reactor comprises a hollow tube that containsthe particulate polymer. The tube reactor is held at an angle to thehorizontal, and the particulate polymer passes through the tube throughgravitational action. The tube angle determines the flow rate of theparticulate through the tube. The tube is rotated in order to distributeindividual particles evenly and expose all particles to the reactants.The tube reactor design permits the particulate polymer to flow in anear plug-flow condition, and is particularly suitable for continuousoperations. The reactants are introduced individually and sequentiallythrough the tube, preferentially countercurrent to the direction of theparticulate polymer.

[0026] Polymer particles treated according to the invention preferablyare non-agglomerated. By “non-agglomerated”, it means that the particlesdo not form significant amounts of agglomerates during the process ofcoating the substrate particles with the inorganic material. Particlesare considered to be non-agglomerated if (a) the average particle sizedoes not increase more than about 5%, preferably not more than about 2%,more preferably not more than about 1% (apart from particle sizeincreases attributable to the coating itself) as a result of depositingthe coating, or (b) if no more than 2 weight percent, preferably no morethan 1 weight % of the particles become agglomerated during the processof depositing the inorganic material.

[0027] Because the reaction precursors are all in the gas phase, the ALDprocess is not a “line-of-sight” method of depositing the multiplebilayers. Instead, the reactants can cover all surfaces of thesubstrate, even if those surfaces are not in the direct path of theprecursors as they are brought into the reaction chamber and removed.Further, as the reactions are self-limiting, and the precursors formonly monolayer deposits on the substrate surface during each exposure,the resulting deposit that is applied per reaction cycle is highlyuniform in thickness. This permits the formation of high qualitydeposits on surfaces of substrates that have a wide range of geometries.

[0028] The selection of reactants is important in obtaining goodadhesion of the inorganic material. At least one of the reactants ispreferably one that which, if contacted in bulk with the polymersubstrate, will wet the surface of the polymer substrate (a ‘wetting’reactant). If the polymer substrate contains functional groups, thefirst reactant may also be reactive with those functional groups at thereaction temperatures described before, thereby forming a surfacespecies that is chemically bonded to the polymer and capable of engagingin further reactions to form the inorganic material.

[0029] Although the invention is not limited to any theory, it isbelieved that a wetting reactant will sorb onto the surface of thepolymer substrate when applied under ALD conditions. The wettingreactant tends to penetrate somewhat beneath the surface of the polymer,such as into small pores or imperfections in the polymer surface, oreven between polymer chains at a molecular level. Wetting reactantmolecules thus sorbed onto the polymer surface to create sites at whichthe other reactants can attach and react to form the inorganic material.If one of the ALD reactants will sorb onto the polymer surface, it ispossible to conduct the ALD reaction sequence and form adherentinorganic coatings, even if one or more of the other ALD reactants doesnot wet the polymer surface. For example, ALD sequences that use wateras a reactant can be successfully conducted even on highly non-polarsubstrates such as polyolefins or organosilicones, if a wetting reactantsuch as trimethyl aluminum is used.

[0030] Because the polymer surface tends to have small pores andimperfections, the inorganic material often is deposited discontinuouslyor unevenly at first, until a number of reaction cycles have beencompleted. However, as more reaction cycles are repeated, individualdeposits of inorganic material tend to grow together and interconnect toform a continuous coating. Thus, by selection of the polymer substrateand the number of times the ALD reaction sequence is conducted, theinorganic deposits may be formed as a plurality of individual particlesor a continuous or semi-continuous film. It is believed, again withoutlimiting the invention to any theory, that by interconnecting individualdeposits of inorganic material that are formed in the first few reactioncycles, the inorganic material forms “bridges” between these deposits.These “bridges” can mechanically interlock with the polymer substrate(at a molecular or larger scale) and secure the inorganic deposits tothe substrate in that manner. This mechanical interlocking may besupplemented by chemical bonding in cases where the polymer hasfunctional groups that can form bonds to one or more of the ALDreactants. This effect is illustrated in Examples 2-4 below, in whichlarge reactant uptakes are seen during early reaction cycles, followedby smaller uptakes during later reaction cycles as a continuousinorganic film is created and the reactants can no longer penetrate intopores in the polymer substrate.

[0031] Trimethylaluminum (TMA) is sorbed well onto a wide variety ofpolymer substrates, including nonpolar polymers such as polyolefins,poly (alkenyl aromatics) and organo silicone polymers. As such, an ALDprocess using TMA as a reactant is particularly suitable for depositinginorganic materials onto a wide range of organic polymers. TMA ALDreactions usually form alumina (Al₂O₃); an illustrative example of anoverall reaction of this type is 2Al(CH₃)₃+3H₂O -->Al₂O₃+6CH₄. In theALD process, this reaction is conducted as half-reactions as follows(following initial introduction of TMA onto the polymer surface):

Al—(CH₃)*+H₂O→4Al—OH*+CH₄  (A1)

Al—OH*+Al(CH₃)₃→Al—O—Al(CH₃)₂*+CH₄  (B1)

[0032] The asterisk (*) indicates a species at the surface of theinorganic material. This particular sequence of reactions to depositalumina is particularly preferred, as the reactions can proceed attemperature below 350K. This particular reaction sequence tends todeposit Al₂O₃ at a rate of ˜1.2 Å per AB cycle. On polymer substrates, asomewhat greater rate of growth is often seen, especially during thefirst 25-50 AB reaction cycles. This is believed to be due to thepenetration of the TMA into the polymer substrate and formation ofdiscontinuous Al₂O₃ deposits during the initial reaction cycles.Triethyl aluminum (TEA) can also be used in place of TMA in the reactionsequence.

[0033] Many ALD reaction sequences do not include a good wettingreactant. It is still possible in such cases to deposit the desiredinorganic material onto the polymer substrate. One way of accomplishingthis is to deposit a “precursor” inorganic material onto the substrate,via an ALD reaction sequence that includes a good wetting reactant.Reactive species on the precursor inorganic material can become reactivesites at which a second ALD sequence can be initiated to deposit thedesired inorganic material. A particularly suitable “precursor”inorganic material is alumina, which is preferably deposited usingreaction sequence A1/B1 above. As few as two repetitions of a reactioncycle forming a “precursor” inorganic material can be used. A preferrednumber of reaction cycles to deposit a “precursor” inorganic material isfrom 2 to about 200 cycles, especially from about 5 to about 25 reactioncycles.

[0034] Examples of binary reaction sequences for producing metal layersare described in copending application Ser. No. 09/523,491 entitled “ASolid Material Comprising a Thin Metal Film on its Surface and Methodsfor Producing the Same”. A specific reaction scheme described thereininvolves sequential reactions of a substrate surface with a metal halidefollowed by a metal halide reducing agent. The metal of the metal halideis preferably a transition metal or a semimetallic element, includingtungsten, rhenium, molybdenum, antimony, selenium, tellurium, platinum,ruthenium and iridium. The halide is preferably fluoride. The reducingagent is suitably a silylating agent such as silane, disilane, trisilaneand mixtures thereof. Other suitable reducing agents are boron hydridessuch as diborane.

[0035] For depositing a tungsten coating, for instance, the overallreaction, WF₆+Si₂H₆→W+2SiF₃H+2H₂, can be split into a sequence ofreactions represented as follows. As neither of the reactants is a goodwetting reactant, an alumina adhesion layer can be formed first asdescribed above. The alumina layer will contain Al—OH surface speciesthat form sites to initiate the tungsten-forming reactions

Al—OH* (substrate surface)+Si₂H₆→Al—O—SiH₃*+SiH₄

Al—O—SiH₃*+WF₆→Al—O—WF₅*+SiFH₃  (precursor reactions)

Al—O—WF₅*+Si₂H₆→Al—O—W—SiF₂H*+SiF₃H+2H₂  (A2)

Al—O—W—SiF₂H*+WF₆→Al—O—W—WF₅+SiF₃H  (B2)

[0036] The asterisk (*) indicates the species that resides at thesurface of the substrate or applied film. Once the precursor reaction iscompleted, reactions A2 and B2 are alternatively performed until atungsten layer of desired thickness is formed.

[0037] Another binary reaction scheme suitable for depositing a metal(M²) film on an alumina adhesion layer can be represented as:

Al*—O—H (substrate surface)+M²X_(n)→Al—O—M²*X_(n−1)+HX  (precursorreaction)

Al—O-M²X*+H₂→Al—O-M²-H*+HX  (A₃)

Al—O-M²-H*+M²(acac)→Al—O-M²-M²*(acac)+H(acac)  (B3)

[0038] “Acac” refers to acetylacetonate ligand, and X is a displaceablenucleophilic group. Also as before, the asterisk (*) refers to thespecies residing at the surface. By heating to a sufficient temperature,hydrogen bonded to the surface as M²-H will thermally desorb from thesurface as H₂, thereby generating a final surface composed of M² atoms.Cobalt, iron and nickel are preferred metals for coating according toreaction sequence A3/B3.

[0039] Oxide layers can be prepared on an underlying substrate or layerhaving surface hydroxyl or amine groups using a binary (AB) reactionsequence as follows. In the sequences below, R represents an atom on thesurface of the polymer substrate. In the case where an alumina or otheradhesion layer is used, R represents a metal atom (aluminum in the casewhere the adhesion layers is alumina). If no adhesion layer is used, Rrepresents an atom on the polymer. The asterisk (*) indicates the atomthat resides at the surface, and Z represents oxygen or nitrogen (oxygenin the case where an alumina adhesion layer is used). M¹ is an atom ofthe metal (or semimetal such as silicon), particularly one having avalence of 3 or 4, and X is a displaceable nucleophilic group. Thereactions shown below are not balanced, and are only intended to showthe reactions at the surface of the particles (i.e., not inter- orintralayer reactions).

R-Z-H*+M¹X_(n)→R-Z-M¹X_(n−1)*+HX  (A4)

R-Z-M¹X*+H₂O→R-Z-M¹OH*+HX  (B4)

[0040] In reaction A4, reagent M¹X_(n) reacts with the R*-Z-H groups onthe surface to create a new surface group having the form -M¹-X_(n−1).M¹ is bonded through one or more Z (nitrogen or oxygen) atoms. The-M¹-X_(x−1) group represents a site that can react with water inreaction B4 to regenerate one or more hydroxyl groups. The hydroxylgroups formed in reaction B4 can serve as functional groups throughwhich reactions A4 and B4 can be repeated, each time adding a new layerof M¹ atoms. Note that in some cases (such as, e.g., when M¹ is silicon,zirconium, titanium, boron or aluminum) hydroxyl groups can beeliminated as water, forming M¹-O-M¹ bonds within or between layers.This condensation reaction can be promoted if desired by, for example,annealing at elevated temperatures and/or reduced pressures.

[0041] Binary reactions of the general type described by equations A4and B4, where M¹ is silicon, are described more fully in J. W. Klaus etal, “Atomic Layer Controlled Growth of SiO₂ Films Using Binary ReactionSequence Chemistry”, Appl. Phys. Lett. 70, 1092 (1997) and O. Sheh etal., “Atomic Layer Growth of SiO₂ on Si(100) and H₂O using a BinaryReaction Sequence”, Surface Science 334, 135 (1995). Binary reactions ofthe general type described by equations A4 and B4, where M¹ is aluminum,are described in A. C. Dillon et al, “Surface Chemistry of Al₂O₃Deposition using Al(CH₃)₃ and H₂O in a Binary reaction Sequence”,Surface Science 322, 230 (1995) and A. W. Ott et al., “Al₂O₃ Thin FilmGrowth on Si(100) Using Binary Reaction Sequence Chemistry”, Thin SolidFilms 292, 135 (1997). General conditions for these reactions asdescribed therein can be adapted to construct SiO₂ and Al₂O₃ coatings onparticulate materials in accordance with this invention. Analogousreactions for the deposition of other metal oxides such as, TiO₂ andB₂O₃ are described in Tsapatsis et al. (1991) Ind. Eng. Chem. Res.30:2152-2159 and Lin et al., (1992), AIChE Journal 38:445-454.

[0042] Other reaction sequences can be performed to produce nitride andsulfide coatings. An illustrative reaction sequence for producing anitride coating is:

R-Z-H*+M¹X_(n)→R-Z-M¹X_(n−1)*+HX  (A5)

R-Z-M¹X*+NH₃→R-Z-M¹NH₂*+HX  (B5)

[0043] Ammonia can be eliminated to form M¹-N-M¹ bonds within or betweenlayers. This reaction can be promoted if desired by, for example,annealing at elevated temperatures and/or reduced pressures.

[0044] An illustrative reaction sequence for producing a sulfide coatingis:

R-Z-H*+M¹X_(n)→R-Z-M¹X_(n−1)*+HX   (A6)

R-Z-M¹X*+H₂S→R-Z-M¹SH*+HX   (B6)

[0045] Hydrogen sulfide can be eliminated to form M¹—S—M¹ bonds withinor between layers. As before, this reaction can be promoted by annealingat elevated temperatures and/or reduced pressures.

[0046] A suitable binary reaction scheme for depositing an inorganicphosphide coating is described in Ishii et al, Crystal. Growth 180(1997) 15.

[0047] In the foregoing reaction sequences, suitable replaceablenucleophilic groups will vary somewhat with M¹, but include, forexample, fluoride, chloride, bromide, alkoxy, alkyl, acetylacetonate,and the like. Specific compounds having the structure M¹X_(n) that areof particular interest are silicon tetrachloride,tetramethylorthosilicate (Si(OCH₃)₄), tetraethyl-orthosilicate(Si(OC₂H₅)₄), trimethyl aluminum (Al(CH₃)₃), triethyl aluminum(Al(C₂H₅)₃), other trialkyl aluminum compounds, and the like.

[0048] In addition, catalyzed binary reaction techniques such asdescribed in U.S. Pat. No. 6,090,442 are suitable for producingcoatings, especially oxide, nitride or sulfide coatings, most preferablyoxide coatings. Reactions of this type can be represented as follows:

R—OH+C₁→R—OH^(...)C₁  (A7a)

R—OH^(...)C₁+R¹-M¹-R¹→R—O-M¹-R¹+R¹—H+C₁  (A7b)

R—O-M¹-R¹+C₂→R—O-M¹-R^(1...)C₂  (B7a)

R—O-M¹-R^(1...)C₂+H₂O→R—O-M¹-OH+R¹—H+C₂  (B7b)

[0049] C₁ and C₂ represent catalysts for the A7b and B7b reactions, andmay be the same or different. Each R¹ represents a functional group(which may be the same or different), and M and M¹ are as definedbefore, and can be the same or different. Reactions A7a and A7b togetherconstitute the first part of a binary reaction sequence, and reactionsB7a and B7b together constitute the second half of the binary reactionsequence. An example of such a catalyzed binary reaction sequence is:

Al—OH* (adhesion layer)+C₅H₅N→Al—OH^(...)C₅H₅N*  (A8a)

Al—OH^(...)C₅H₅N*+SiCl₄→Al—O—SiCl₃*+C₅H₅N+HCl  (A8b)

Al—O—SiCl₃*+C₅H₅N→Al—O—SiCl₃ ^(...)C₅H₅N*   (B8a)

Al—O—SiCl₃ ^(...)C₅H₅N*+H₂O→Al—O—H*+C₅H₅N+HCl   (B8b)

[0050] where the asterisks (*) again denote atoms at the surface. Thisgeneral method is applicable to forming various other coatings,including silica, zirconia or titania.

[0051] Several techniques are useful for monitoring the progress of theALD reactions. For example, vibrational spectroscopic studies can beperformed on high surface area silica powders using transmission Fouriertransform infrared techniques. The deposited coatings can be examinedusing in situ spectroscopic ellipsometry. Atomic force microscopystudies can be used to characterize the roughness of the coatingrelative to that of the surface of the substrate. X-ray photoelectronspectroscopy and x-ray diffraction can by used to do depth-profiling andascertain the crystallographic structure of the coating.

[0052] The inorganic deposits formed in the ALD process may take theform of individual particles or a continuous or semi-continuous film.The physical form of the deposits will depend on factors such as thephysical form of the polymer substrate and the number of times thereaction sequence is repeated. It has been found that very often, theinorganic material formed in the first one or several reaction sequencestends to be deposited discontinuously. As the reaction sequences arecontinued, the initially discontinuous deposits will often becomeinterconnected as further inorganic material is deposited.

[0053] In many preferred embodiments, the deposits of inorganic materialform an ultrathin conformal coating. By “ultrathin”, it is meant thatthe thickness of the coating is up to about 100 nm, more preferably fromabout 0.1 to about 50 nm, even more preferably from about 0.5-35 nm andmost preferably from about 1 and about 20 nm. These thicknesses providea flexible coating that provides good vapor and gas barrier properties.By “conformal” it is meant that the thickness of the coating isrelatively uniform across the surface of the particle (so that, forexample, the thickest regions of the coating are no greater than 3×,preferably no greater than 1.5× the thickness of the thinnest regions),so that the surface shape of the coated substrate closely resembles thatof the underlying substrate surface. Conformality is determined bymethods such as transmission electron spectroscopy (IEM) that haveresolution of 10 nm or below. Lower resolution techniques cannotdistinguish conformal from non-conformal coatings at this scale. Thedesired substrate surface is also preferably coated substantiallywithout pinholes or defects.

[0054] The applied inorganic material can impart many desirableproperties to the polymer substrate, depending on the particularsubstrate, inorganic material and end-use application. In manyinstances, the inorganic material forms a continuous film on the surfaceof the polymer substrate. This continuous film can form a barrier todiffusion of gasses and vapors such as hydrocarbons, water and oxygen,through the coated polymer. When the polymer substrate is a film, thecoated polymer can be readily fabricated into packaging films, bags,bottles, other types of storage containers, gloves, protective clothing,or other types of products in which barrier properties are desired.These packaging materials are particularly suitable for packaging food,medicines or other materials that are prone to dehydration or oxidativedegradation. The ultrathin inorganic layers form excellent diffusionbarriers because the ultrathin films are quite flexible. The ultrathinfilms are therefore less susceptible to forming microcracks and thusbecoming more gas permeable than thicker layers applied using othermethods.

[0055] Good barrier properties are seen when a continuous film ofinorganic material of a thickness of about 10 nm or more, preferablyabout 20-100 nm, and more preferably about 20-50 nm is deposited.

[0056] Alternatively, a barrier layer of the inorganic material may beapplied using the aforementioned ALD methods to a previously-fabricatedbag, bottle or other type of storage container, glove or protectivearticle of clothing. Yet another way to make these articles is todeposit the inorganic coating on polymer particles, and then fabricate apolymer film on the article itself from the coated polymer particles.Combinations of these methods can be used to create a barrier layer thatis dispersed throughout the polymer and also on the surface of thefabricated article.

[0057] Another application for which barrier properties are desirableare inflatable objects such as tennis balls, other athletic equipment,balloons, pneumatic tires and the like. Elastomeric polymers such asbutyl rubber can be coated with an inorganic film according to theinvention to form a material suitable as a barrier layer for suchinflatable objects.

[0058] The deposited inorganic material may also serve as an adhesionlayer, through which other inorganic materials can be adhered to thepolymer substrate. In cases where the polymer has no functional groupsthat react with the ALD reactants, the deposition of an inorganicmaterial such as alumina can provide such functional groups. SubsequentALD reactions can take advantage of the functional groups provided bythe first-deposited inorganic material, reacting with them to form astrong cohesive bond.

[0059] An example of such an embodiment is the deposition of a diffusionbarrier layer such as TiN or TaN on low k dielectric polymers.Semiconductor devices often use aluminum alloy interconnects insulatedwith SiO₂ dielectric layers. As semiconductor devices are fabricatedwith smaller dimensions, the resistance capacitance (RC) time constantof the interconnects eventually limits the device speed. One strategyfor reducing the RC time constant is to replace the aluminum withcopper.

[0060] Further improvements in device performance are achieved byreducing the capacitance of the dielectric volume between theinterconnect lines. This may be accomplished by changing from SiO₂ to alower dielectric constant material (a “low-k” material). Organicpolymers are being considered as low-k materials. A problem with usingorganic polymers as low-k materials is copper diffusion. Copper atomscan migrate from the interconnects through the organic polymer at hightemperatures in the presence of electric fields and cause devicefailure. Diffusion barrier materials such as TiN may be deposited on theorganic polymer prior to the copper deposition to prevent copperdiffusion. The diffusion barrier material should be continuous andpreferably is conformal to ensure a uniform coating.

[0061] The deposited inorganic material may provide an electricalinsulating or conducting layer on the polymer substrate. Conductingpolymers are used in a variety of electronic applications, such asorganic light emitting diodes (OLEDs). These conducting polymers oftenneed to be isolated from other conducting layers. OLED devices inparticular need insulating layers to define proper device performance. Adeposited film of inorganic material such as Al₂O₃ form an insulatinglayer on such conducting polymers. A deposited Al₂O₃ layer sandwichedbetween conducting polymer layers can provide a means for fabricatingelectron tunneling devices such as electroluminescent displays. Thepolymer substrate allows the display to be flexible.

[0062] An Al₂O₃/ZnO mixture can be used to define conducting layers withvariable resistivity. The Al₂O₃/ZnO alloy system spans a full 18 ordersof magnitude in resistivity, and so, if deposited on a nonconductivepolymer substrate in accordance with this invention, it is possible toprovide conducting layers of controllable conductivity onto a polymersubstrate.

[0063] The deposited inorganic material may also improve some desiredmechanical property of the polymer, such as impact strength, tensilestrength and the like. The inorganic film can also provide corrosionresistance to the polymer substrate.

[0064] Polymer particles according to the invention may be formed into adispersion in an aqueous and/or organic liquid phase for making coatingsfor a wide range of coating applications.

[0065] The deposited inorganic material in many cases can serve as aprotective coating for the polymer substrate. For example, the coatingin many cases imparts ultraviolet, chemical, or erosion barrierproperties to the coated polymer. These barrier properties can improveor extend the useful life of polymers that are used as structuralcomponents in a wide variety of appliance, vehicle or constructionapplications, for example. The inorganic material may be deposited onmolded parts made from a variety of structural and engineering polymers,or may be deposited onto polymer sheets or particles that aresubsequently shaped to form the structural components.

[0066] Polymer particles made according to the invention are useful formaking nanocomposites and/or organic/inorganic alloys. One way of makingthe nanocomposites is to melt process the coated particles. “Meltprocessing” involves any method by which the particles are meltedtogether to form a molten mass, such as, for example, any extrusion ormelt spinning or molding process. The molten mass may be formed directlyinto some desired article, or may be extruded and formed into pellets orparticles for later fabrication. The melt processing intimately mixesthe inorganic material into the polymer in the form of nano-scaleparticles. The melt-processed polymer may then be fabricated in anysuitable manner to form a structural component for appliance, vehicle orconstruction applications, among others. The resulting nanocompositewill in most cases have higher impact strength than the neat polymersubstrate. This method of forming nanocomposites overcomes many of thedifficulties seen with conventional methods of making nanocomposites,because it is no longer necessary to defoliate the reinforcing materialand disperse it into the polymer.

[0067] In other cases, the nano-dispersed particles can provide improvedflame retardancy to the polymer. In particular, polymer particlesaccording to the invention that have a deposited metal coating can beextruded to form a nanocomposite which, if combined withphosphorous-containing flame retarding compounds, have decreased polymerflammability and increased charring on fire testing. Oxide coatingsapplied to polymer particles according to the invention can result insimilarly increased charring upon fire testing, with or withoutadditional flame retardant.

[0068] In another application, the polymer particles coated according tothe invention can be used to encapsulate electronic parts. Of particularinterest are solid epoxy resins that are coated with alumina. Thealumina layer enhances the compatibility of the polymer particles withvarious fillers such as AlN, BN or Si₃N₄. It is further possible toapply a coating of these nitrides to the polymer particles themselves(preferably using an alumina adhesion layer).

[0069] In yet another application, an active catalyst can be depositedonto the coated polymer particles of the invention to form a supportedcatalyst with the polymer particles as the support. Particularlysuitable polymers for this purpose are crosslinked materials, inparticular crosslinked polystyrene polymers as are used in gel- and/ormacroporous-type ion exchange resins. The crosslinked polymers maycontain functional groups (such as primary or secondary amino, carboxylor sulfonate groups) that serve as initiation points for the depositionof the inorganic material. Several embodiments of the invention areuseful in this application. In one embodiment, the catalytic material,which is typically a metal such as platinum, palladium, cobalt, zinc,magnesium, tungsten, and the like, is deposited onto the polymersubstrate using ALD methods as described herein. An alumina, silica orother adhesion layer is preferred because metals tend to bind to aluminaand silica surfaces well. The adhesion layer thus promotes the loadingof the polymer particles with the metallic catalyst. Since atomic layerdeposition is not line-of-sight dependent, it is possible for thecoatings to be placed along the inner walls of pores within the catalystparticles. In other embodiments, an adhesion layer is deposited onto thepolymer substrate as described before, and the catalytic material isdeposited onto the coated polymer particles using some other technique.A chemical reaction is then conducted in the presence of particlescoated with a metal that is a catalyst for the reaction. An example ofsuch a reaction is a gas phase polymerization.

[0070] The inorganic material in many cases alters the surfaceproperties of the polymer substrates without altering their bulkproperties. For example, the coatings sometimes passivate reactivepolymer surfaces and provide a barrier to protect the bulk materials orthe contents within the bulk materials from the surrounding environment.If the coatings are placed on polymer particles, prior to fabricatingcomponents from the particles, it is possible for the coatings to beintimately blended in the polymer matrix and improve the properties ofthe fabricated component. Rather than strictly improved chemicaleffects, it is also possible for the coatings to provide desirablephysical or structural property that the bulk material does not possess.

[0071] Polymer particles according to the invention can also be used toform coatings in flame spraying and other processes. Particles havingTiO₂ coatings may act as photoinitiated catalysts to oxidize dirtdeposits and provide a self-cleaning coating. Such particles may be usedas a paint additive for that purpose. Particles having a metal coatingcan provide metallic and/or pearlescent effects for metallic finishes,and can be used as additives in paint formulations for that purpose.Particles having a variety of inorganic coatings can be used asadditives for improving scratch and wear resistance in paints andcoatings.

[0072] Coatings of particular interest are so-called “solventless” or“powder” coatings. In powder coating applications, a dry, particulatepowder is applied to some substrate that is to be coated, and theapplied powder is then melted to coalesce the particles into a smoothfilm. Specific applications include coating for wood furniture,prefinished wood floors, coatings for optical fibers, vinyl flooringcovers, metal coatings (such as automobile exterior body parts), andglass coatings. Both thermoset and thermoplastic types are used,including polyurethanes, epoxies, polyesters, melamine-vinyl etherresins, and the like. In some cases, the film then undergoes a curingstep, in which a chemical curing agent or energy (typically a source ofheat or UV light) is applied in order to complete the curing of thefilm. Melting and/or curing is typically done at temperatures of350-400° F., but due to safety and handling considerations, it isdesirable to reduce those temperatures into the range of 250-300° F. Ithas been found that lower-curing powder coating materials tend toagglomerate when stored, even at ordinary room temperatures. Thisproblem of low-temperature agglomeration is overcome using thisinvention. A continuous coating of an inorganic material, applied asdescribed herein, effectively prevents the polymer particles fromadhering to each other at low temperatures. Because the inorganiccoating is extremely thin, it still allows the particles to melttogether at higher temperatures to form a good quality film. In manycases where an inorganic pigment (such as TiO₂) is used in the coatingformulation, the inorganic coating can double as a pigment, reducing oreven eliminating the need for additional pigments to be added to thecoating formulation.

[0073] In yet another application, a polymer film is coated with analumina or other adhesion layer, and a titanium nitride or tantalumnitride layer is deposited, using ALD or other methods, onto theadhesion layer. The resulting structure is a useful polymer substratefor plastic microelectronic packaging. The titanium or tantalum nitridelayer functions as a copper diffusion barrier. The inorganic layer mayalso facilitate the etching of metals more easily than could be achieveddirectly on the polymer surface. Other forms of microelectronicpackaging can be made by depositing other inorganics onto a polymerfilm, with or without an adhesion layer.

[0074] The following examples are provided to illustrate the invention,and are not intended to limit the scope thereof. All parts andpercentages are by weight unless otherwise indicated.

EXAMPLE 1

[0075] Low density polyethylene particles (LDPE) with a diameter of ˜2microns were mounted in a tungsten screen and positioned in a vacuumchamber designed for Fourier transform infrared (FTIR) experiments. Thetemperature of the LDPE particles is controlled by resistive heating ofthe tungsten screen.

[0076] The Al₂O₃ ALD was performed at 350 K, using the reaction sequenceA1/B1 described above. FTIR was used to monitor the progress of thereactions. Prior to beginning the reaction sequence, the FTIR spectra ofthe LDPE particles exhibited prominent C—H stretching vibrations at2960-2840 cm⁻¹ and the C—C stretching vibrations at 1465 cm⁻¹.Additional vibrational features attributed to the polyethylenehydrocarbon chains were observed at 720, 1110, 1300, and 1375 cm⁻¹. TheLDPE particles were first exposed to H₂O at 350 K Because of thehydrophobic nature of the LDPE particles, no vibrational featuresassociated with H₂O, in particular the O—H vibrational stretchingfeatures, were observed by FTIR following the initial H₂O exposure.

[0077] The LDPE particle is then exposed to the TMA reactant at 350K.The FTIR difference spectrum reveals new vibrations at ˜2900 cm−1 thatare assigned to the C—H stretching vibrations from the CH₃ speciesderived from TMA. The FTIR data confirms that TMA either adsorbs on thepolyethylene particles or reacts with species on the polyethylenesurface. When the particles are then exposed to water, the FTIRdifference spectrum exhibits a new vibrational feature at 2900-3600 cm⁻¹attributed to O—H stretching vibrations. In addition, the C—H stretchingvibrations at ˜2900 cm⁻¹ that were added by TMA were removed by the H₂Oreaction. The FTIR spectrum confirms that water has reacted with the TMAat the particle surface.

[0078] As the TMA/H₂O cycles are continued, the growth of an Al₂O₃ bulkvibrational feature begins to appear at 500-950 cm⁻¹. This feature growsprogressively as the reaction cycles are repeated, establishing thatAl₂O₃ is being deposited on the LDPE particles.

[0079] Further confirmation of the deposition of an Al₂O₃ film on theLDPE particles is provided by transmission electron microscopy (TEM)images of the Al₂O₃-coated LDPE particles. TEM images recorded after 40reaction cycles at 350 K indicate an Al₂O₃ film of between 150-200 Å wasproduced. This thickness was greater than expected after 40 AB cycles.This thicker Al₂O₃ film is attributed to the diffuse nature of the LDPEsurface and near surface region. TMA is believed to diffuse into thepolymer chain network near the surface of the LDPE particle. The TMA maysimply be adsorbed in this region or may react with carbon radicals.Consequently the TMA becomes distributed over a relatively wide zone inthe near surface region of the LDPE polymer, causing the depositedalumina film to be similarly formed over this wide zone.

EXAMPLE 2

[0080] The atomic layer deposition of Al₂O₃ on polymethyl methacrylate(PM), polyvinylchoride (PVC) and polypropylene (PP) was performed usingquartz crystal microbalance (QCM) studies. QCM methods are verysensitive to mass and can easily measure mass changes of ˜0.3 ng/cm²that correspond to the deposition of fractions of an atomic layer ofAl₂O₃. By spin-coating various polymer films onto the QCM sensor, theadsorption of various chemical species can be measured accurately onpolymer films. Likewise, the growth of thin films on polymer films canalso be monitored with extreme precision.

[0081] The thickness of the PEA film on the QCM sensor used in thisExample is 1300 Å. The Al₂O₃ ALD is performed at 86° C. using at₂-t₂-t₃-t₄ pulse sequence of 1-20-1-20. t₁ is the trimethylaluminum(TMA) reactant pulse, t₂ is the purge time after the TMA pulse, t₃ isthe H₂O reactant pulse and t₄ is the purge time after the H₂O pulse. Alltimes are in seconds.

[0082] Mass measurements during the ALD process reveal a large massincrease during TMA reactant exposure. Subsequently, the mass decreasesduring the purge time after the TMA pulse. This mass decreasecorresponds to the loss of some of the absorbed TMA. The mass decreaseis stopped with the introduction of the H₂O reactant pulse. However,there is no obvious increase in mass corresponding with the H₂O reactantpulse, which is consistent with the replacement of —CH₃ groups with —OHgroups.

[0083] The second TMA reactant pulse again leads to an increase in theQCM mass. Likewise, mass is lost during the purge after the second TMApulse. The behavior following the second H₂O reactant pulse is alsosimilar. However, the total mass has increased following the second H₂Oreactant pulse. This mass increase corresponds to the growth of Al₂O₃ onthe PMMA polymer film. Subsequent TMA/H₂O reactant cycles displaysimilar behavior. The total mass increases following each TMA/H₂Oreactant cycle, indicating the growth of the Al₂O₃ layer. The pronouncedmass increases during the TMA reactant exposures are progressivelyreduced in magnitude during the first 20 TMA/H₂O reactant cycles. Afterthese 20 TMA/H₂O reactant cycles, only a small mass increase occursduring the TMA reactant pulse and no pronounced mass reduction occursduring the purge following the TMA reactant pulse. This behaviorsuggests that the Al₂O₃ ALD film deposited during the first 15-20TMA/H₂O reactant cycles has formed a diffusion barrier at the PMMApolymer surface that impedes the diffusion of TMA into the polymer.Because the TMA can no longer penetrate into the polymer, it can onlydeposit at the surface. For that reason, TMA uptake becomes less as thenumber of reaction cycles increases. After about 20 TMA/H₂O reactantcycles, the growth of the mass with number of TMA/H₂O reactant cycles isessentially linear. This linear mass increase with number of TMA/H₂Oreactant pulses will continue indefinitely with the repetitive pulsesequence because the Al₂O₃ film has formed a diffusion barrier on thePMMA polymer surface.

EXAMPLE 3

[0084] Example 2 is repeated, this time using a polypropylene filmdeposited on the QCM sensor at a thickness of ˜6000 Å. The Al₂O₃ ALD isperformed at 80° C., again using a t₁-t₂-t₃-t₄ pulse sequence of1-20-1-20. Similar to the results in Example 2, the TMA reactant pulseleads to a large increase in the mass recorded by the QCM. The massdecreases during the purge following the TMA reactant pulse. Thisbehavior is again explained as the diffusion of TMA into the PP polymerduring the TMA reactant pulse. Subsequently, some of the TMA diffusesout during the purge following the TMA reactant pulse. Repeating TMA andH₂O reactant pulses leads to a progressive increase of mass associatedwith the growth of Al₂O₃. However, the magnitude of the mass increaseduring the TMA reactant pulses decreases versus number of TMA/H₂Oreactant cycles. This decrease in magnitude is attributed to the growthof the Al₂O₃ ALD film. The Al₂O₃ ALD film serves as a diffusion barrierand impedes the diffusion of TMA into the PP polymer film. After ˜15TMA/H₂O reactant cycles, the mass increases very linearly with number ofTMA/H₂O reactant cycles. The mass increase during the TMA reactant pulsebecomes reduced. Both of these observations are consistent with an Al₂O₃diffusion barrier being formed during the first 15 TMA/H₂O reactantcycles. Once the Al₂O₃ ALD diffusion barrier is established on the PPpolymer surface, the Al₂O₃ ALD film grows linearly as expected for Al₂O₃ALD on a flat oxide surface.

EXAMPLE 4

[0085] Example 2 is again repeated, this time using a polyvinylchoride(PVC) polymer film. Very similar behavior was observed in comparison toAl₂O₃ ALD on PMMA and PP as shown in Examples 2 and 3. The Al₂O₃deposition was performed at 80° C. using a t₁-t₂-t₃-t₄ pulse sequence of1-20-1-20.

[0086] The TMA readily diffuses into the PVC polymer during the TMAreactant pulse. However, in contrast to the results on PMMA and PP, theTMA does not diffuse out during the purge time after the TMA reactantpulse. This behavior indicates that TMA is more strongly absorbed by PVCthan by PMMA or PP. Large amounts of TMA are absorbed during the initialTMA/H₂O reactant cycles. After approximately 15 TMA/H₂O reactant cycles,the large mass increases are no longer observed during the TMA reactantpulses. This behavior indicates that an Al₂O₃ diffusion barrier has beenformed on the PVC polymer film. For additional TMA/H₂O reactant cycles,the mass increases linearly as expected for the growth of an Al₂O₃ ALDfilm.

1. A method for depositing an inorganic material on a polymer substratematerial comprising conducting a sequence of at least two self-limitingreactions at the surface of said polymer substrate to deposit theinorganic material onto the surface of said polymer substrate.
 2. Themethod of claim 1, wherein said self-limiting reactions are conducted ata temperature below the temperature at which the polymer substratedegrades, melts or softens enough to lose its physical shape, and theself-limiting reactions are conducted using reactants that are gassesunder the conditions of the reactions
 3. The method of claim 2, which isan ALD process.
 4. The method of claim 3, wherein at least one of thereactants wets the surface of the polymer substrate.
 5. The method ofclaim 3, wherein the polymer substrate is in the form of a film.
 6. Themethod of claim 3, wherein the polymer substrate is in the form of aparticulate.
 7. The method of claim 6, wherein the method is conductedby fluidizing a bed of the particulate polymer substrate.
 8. The methodof claim 3, wherein the inorganic material is alumina. 9 (canceled). 10.The method of claim 8, wherein an additional inorganic material isdeposited over the alumina.
 11. The method of claim 3, wherein theinorganic material is deposited in the form of a continuous film. 12.The method of claim 11, wherein the continuous film is ultrathin andconformal.
 13. The method of claim 12, wherein the continuous film has athickness of from 0.5 nanometer to 200 nanometers.
 14. The method ofclaim 3 wherein the polymer substrate contains functional groups throughwhich the inorganic material forms chemical bonds to the polymersubstrate.
 15. The method of claim 14 wherein the functional group ishalogen, hydroxyl, carbonyl, carboxylic acid, primary amine, secondaryamine, or mixture of two or more thereof.
 16. The method of claim 3wherein the polymer substrate is low density polyethylene, linear lowdensity polyethylene, substantially linear polyethylene, high densitypolyethylene, polypropylene, polybutylene, polystyrene,poly(naphthalene); a polymer of a conjugated diene, polyethyleneterephthalate, polymethyl methacrylate, polyvinyl chloride, or anorganosilicone polymer.
 17. A polymer composition comprising polymersubstrate having deposited thereon an inorganic material in the form ofa film or discrete particles having a thickness of 200 nm or less. 18.The polymer composition of claim 17 wherein the inorganic material is inthe form of a continuous film.
 19. The polymer composition of claim 18wherein the continuous film is conformal.
 20. The polymer composition ofclaim 17 wherein the inorganic material is alumina.
 21. The polymercomposition of claim 20 wherein another inorganic material is depositedover the alumina.
 22. A polymer composition comprising a polymersubstrate having an inorganic material deposited thereon made inaccording with method of claim
 1. 23. The polymer composition of claim22 which is fabricated into a bag, bottle or other container.
 24. Thepolymer composition of claim 23 wherein the inorganic material providesa gas and vapor diffusion barrier for the bag, bottle or othercontainer. 25 (canceled). 26 (canceled).
 27. A method comprising meltprocessing the polymer composition of claim 17 to form a fabricatedarticle. 28 (canceled). 29 (canceled). 30 (canceled).
 31. The polymercomposition according to claim 22, in which the inorganic material isalumina.
 32. The polymer composition according to claim 31, in which asecond inorganic material is deposited over the alumina.
 33. The polymercomposition of claim 32, in which the second inorganic material forms anultrathin, conformal coating.
 34. The polymer composition of claim 32,in which the second inorganic material is titanium nitride or tantalumnitride. 35 (canceled). 36 (canceled). 37 (canceled).